1.
What are the two types of Exceptions in Java? Which are the differences between them?
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Xamarin Java interview questions.
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- 2.
What is JVM? Why is Java called the “Platform Independent Programming Language”?
Answer:
- 3.
What is the difference between an Applet and a Java Application?
Answer:
- 4.
What is the Difference between JDK and JRE?
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- 5.
What is a Servlet?
Answer:
- 6.
What is a JSP Page?
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- 7.
What are Directives?
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- 8.
What does System.gc() and Runtime.gc() methods do?
Answer:
- 9.
What differences exist between HashMap and Hashtable?
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- 10.
What is JDBC?
Answer:
- 11.
What does the “static” keyword mean? Can you override private or static method in Java?
Answer:
- 12.
What is the importance of finally block in exception handling?
Answer:
- 13.
What is the difference between Exception and Error in java?
Answer:
- 14.
When does an Object becomes eligible for Garbage collection in Java ?
Answer:
- 15.
What is an Iterator?
Answer:
- 16.
What are pass by reference and pass by value?
Answer:
- 17.
What is an Java Applet?
Answer:
- 18.
How HashMap works in Java?
Answer:
- 19.
What are the basic interfaces of Java Collections Framework?
Answer:
- 20.
What are the Data Types supported by Java? What is Autoboxing and Unboxing?
Answer:
- 21.
What is the difference between processes and threads?
Answer:
- 22.
What will happen to the Exception object after exception handling?
Answer:
- 23.
What is the difference between an Interface and an Abstract class?
Answer:
- 24.
What are Expressions?
Answer:
- 25.
What do you know about the big-O notation and can you give some examples with respect to different data structures?
Answer:
- 26.
What is Function Overriding and Overloading in Java?
Answer:
- 27.
How are the JSP requests handled?
Answer:
- 28.
What is the design pattern that Java uses for all Swing components?
Answer:
- 29.
What is the purpose Class.forName method?
Answer:
- 30.
What is the purpose of garbage collection in Java, and when is it used?
Answer:
- 31.
What’s the difference between sendRedirect and forward methods?
Answer:
- 32.
What are Decalarations?
Answer:
- 33.
What are JSP actions?
Answer:
- 34.
What is reflection and why is it useful?
Answer:
- 35.
Explain the architechure of a Servlet.
Answer:
- 36.
Explain Serialization and Deserialization.
Answer:
- 37.
How does Garbage Collection prevent a Java application from going out of memory?
Answer:
- 38.
How do I efficiently iterate over each entry in a Java Map?
Answer:
- 39.
What is a Constructor, Constructor Overloading in Java and Copy-Constructor?
Answer:
- 40.
What is the role of stub in RMI?
Answer:
- 41.
What is the difference between doGet() and doPost()?
Answer:
- 42.
What is the difference between GenericServlet and HttpServlet?
Answer:
- 43.
Explain the life cycle of a Servlet.
Answer:
- 44.
What is structure of Java Heap?
Answer:
- 45.
What differences exist between Iterator and ListIterator?
Answer:
- 46.
Explain the role of Driver in JDBC.
Answer:
- 47.
What is the relationship between an event-listener interface and an event-adapter class?
Answer:
- 48.
What is the applet security manager, and what does it provide?
Answer:
- 49.
What is the difference between throw and throws?
Answer:
- 50.
What happens when an applet is loaded?
Answer:
- 51.
When is the finalize() called? What is the purpose of finalization?
Answer:
- 52.
Can you access non static variable in static context?
Answer:
- 53.
What is a Server Side Include (SSI)?
Answer:
- 54.
Why Collection doesn’t extend Cloneable and Serializable interfaces?
Answer:
- 55.
Explain the life cycle of an Applet.
Answer:
- 56.
Which Swing methods are thread-safe?
Answer:
- 57.
What is the tradeoff between using an unordered array versus an ordered array?
Answer:
- 58.
What is Comparable and Comparator interface? List their differences.
Answer:
- 59.
What are untrusted applets?
Answer:
- 60.
What are the restrictions imposed on Java applets?
Answer:
- 61.
What is the difference between an Applet and a Servlet?
Answer:
- 62.
How does finally block differ from finalize() method?
Answer:
- 63.
What’s a deadlock?
Answer:
- 64.
What are Scriptlets?
Answer:
- 65.
What’s the difference between Enumeration and Iterator interfaces?
Answer:
- 66.
What is difference between ArrayList and LinkedList ?
Answer:
- 67.
What are the steps involved to make work a RMI program?
Answer:
- 68.
Does Java support multiple inheritance?
Answer:
- 69.
If an object reference is set to null, will the Garbage Collector immediately free the memory held by that object?
Answer:
- 70.
What is the importance of hashCode() and equals() methods?
Answer:
- 71.
Explain different ways of creating a thread. Which one would you prefer and why?
Answer:
- 72.
What is Java Priority Queue?
Answer:
- 73.
What is difference between fail-fast and fail-safe?
Answer:
- 74.
What is difference between Array and ArrayList ? When will you use Array over ArrayList?
Answer:
- 75.
What is the advantage of PreparedStatement over Statement?
Answer:
- 76.
What is meant by JSP implicit objects and what are they?
Answer:
- 77.
How threadsafe is enum in Java?
Answer:
- 78.
What are the differences between == and equals?
Answer:
- 79.
Is there anything like static class in java?
Answer:
- 80.
Compare the sleep() and wait() methods in Java
Answer:
- 81.
How and where are Annotations used in Java?
Answer:
- 82.
What is the difference between final, finalize and finally?
Answer:
- 83.
What is the main difference between StringBuffer and StringBuilder?
Answer:
- 84.
What’s the difference between a ClassNotFoundException and NoClassDefFoundError?
Answer:
- 85.
How can I synchornize two Java processes?
Answer:
- 86.
How do I break out of nested loops in Java?
Answer:
- 87.
What are the advantages of JSP?
Answer:
- 88.
What is the JIT?
Answer:
- 89.
What is a JavaBean exactly?
Answer:
- 90.
Can an enum be extended?
Answer:
- 91.
What is the Java Classloader?
Answer:
- 92.
What is the volatile keyword useful for?
Answer:
- 93.
What is the difference between HashMap, LinkedHashMap and TreeMap in Java?
Answer:
- 94.
What is the difference between public, protected, package-private and private in Java?
Answer:
- 95.
What's the advantage of using getters and setters?
Answer:
- 96.
What is static initializer?
Answer:
- 97.
Is Java “pass-by-reference” or “pass-by-value”?
Answer:
- 98.
Why does Java have transient fields?
Answer:
- 99.
What do the ... dots in the method parameters mean?
Answer:
- 100.
Can == be used on enum?
Answer:
- 101.
What is the use of CallableStatement? Name the method, which is used to prepare a CallableStatement.
Answer:
- 102.
How do I read/convert an InputStream into a String in Java?
Answer:
- 103.
What is Perm Gen space in Heap?
Answer:
- 104.
What is the difference between applets loaded over the internet and applets loaded via the file system?
Answer:
- 105.
What is the role of the java.rmi.Naming Class?
Answer:
- 106.
What is the purpose of using RMISecurityManager in RMI?
Answer:
- 107.
How do you ensure that N threads can access N resources without deadlock?
Answer:
- 108.
What are some of the best practices relating to the Java Collection framework?
Answer:
- 109.
What is meant by binding in RMI?
Answer:
- 110.
What is the role of Remote Interface in RMI?
Answer:
- 111.
What is the difference between a synchronized method and a synchronized block?
Answer:
- 112.
Explain the available thread states in a high-level.
Answer:
- 113.
What is the difference between Serial and Throughput Garbage collector?
Answer:
- 114.
What is the applet class loader, and what does it provide?
Answer:
- 115.
Explain Marshalling and demarshalling.
Answer:
- 116.
How do you find out what client machine is making a request to your servlet?
Answer:
- 117.
What is Servlet Chaining?
Answer:
- 118.
What is the basic principle of RMI architecture?
Answer:
- 119.
What does Connection pooling mean?
Answer:
- 120.
What is Double Brace initialization in Java?
Answer:
- 121.
How do I test a private function or a class that has private methods, fields or inner classes?
Answer:
- 122.
Why is char[] preferred over String for passwords?
Answer:
- 123.
What is RMI?
Answer:
- 124.
What exactly is marker interface in Java?
Answer:
- 125.
What are the differences between a HashMap and a Hashtable in Java?
Answer:
- 126.
When to use LinkedList over ArrayList in Java?
Answer:
- 127.
Why is Spring MVC better than Servlets / JSP ?
Answer:
- 128.
Explain a use case for the Builder Design Pattern
Answer:
- 129.
Does Java support default parameter values?
Answer:
- 130.
What is the main difference between an inner class and a static nested class in Java?
Answer:
- 131.
What is DGC ? And how does it work?
Answer:
- 132.
What is the difference between HashSet and TreeSet?
Answer:
- 133.
How does thread synchronization occurs inside a monitor? What levels of synchronization can you apply?
Answer:
- 134.
Does Garbage collection occur in permanent generation space in JVM?
Answer:
- 135.
What are the layers of RMI Architecture?
Answer:
- 136.
What does 'synchronized' mean?
Answer:
- 137.
What's wrong with Double Brace initialization in Java?
Answer:
- 138.
Why isn’t String‘s .length() accurate?
Answer:
- 139.
Compare volatile vs static variables in Java
Answer:
- 140.
What is an efficient way to implement a singleton pattern in Java?
Answer:
- 141.
What's the difference between SoftReference and WeakReference in Java?
Answer:
- 142.
Why ArrayList are preferable in many more use-cases than LinkedList?
Answer:
- 143.
Provide some examples when a finally block won't be executed in Java?
Answer:
- 144.
Is null check needed before calling instanceof?
Answer:
- 145.
Is it possible to call one constructor from another in Java?
Answer:
- 146.
Given two double values d1, d2, what is the most reliable way to test their equality?
Answer:
- 147.
Explain what will the code return
Answer:
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23 Databases interview questions and answers for software engineers Databases
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